1. Field of the Invention
The invention relates to an arrangement in a remote-controllable subsea connector, especially for use in oil production systems, where the connector components may be locked together by the aid of a collet finger ring and an actuator ring for the fingers, said actuator ring being controlled in the axial direction of said connector.
2. Description of the Prior Art
In subsea systems, especially oil production systems, it is essential that the different components of the system are as reliable as possible and, thus, should also be exchangeable or permit being shut down in a simplest possible manner. This is achieved by dividing the production systems into modules or components which should be easily accessible and permit repairs to be carried out at minimum cost. With such a structure of oil production systems a number of connectors will be used in the pipe systems as well to permit changes being made, components being exchanged, or a pipe being shut down during repair of members, etc.
Great demands are placed on such subsea connectors, not only as regards their reliability and sealing, but as regards remote control as well, which should at the same time safeguard the connector against unintentional release. This may present a problem at great sea depth and, especially, in piping carrying fluids under high pressure.
A number of different connectors have been developed for this object. Thus, a remote-controlled subsea connector is known, where a ring of finger-shaped members is used and placed about the connecting area and which fingers with hook shaped end portions engage in recesses or about flanges on the pipes to be connected. In this connection, it may also, e.g. be a question of a shut down cap of a pipeline. Said collet finger ring conventionally cooperates with an actuator member intended for collecting the fingers of said ring in place to assemble the connector components. Such cooperation is often achieved by the aid of conical exterior faces on said collet finger ring cooperating with corresponding faces on said actuator element and which will press said finger members in place. Conventionally, a cone angle of 4.degree. is used. Due to conicity and interior pressure occurring there will be a tendency for the connection to open-up and for the components to slide apart if the frictional coefficient of the surfaces is too low.
In order to compensate for this locking or blocking members are inserted and these members must be inserted partly with exertion of high force to prevent the finger members from slipping out. Such members may be operated mechanically as well as hydraulically, but they are awkward in use because of the necessity of exact positioning and exertion of relatively high forces. Another known embodiment comprises cooperation between axial faces on the retaining fingers and corresponding axial faces on the actuating element or actuator ring. Such a connection will result in sufficiently secure locking, but it will not be satisfactory as regards a sealed connection with two connector parts being squeezed into mutual engagement and maintained in that state.
The actuator ring elements may be raised and lowered in an axial direction, either by an operating or actuating rod that is provided to form a mechanical connection, or by hydraulic pressure supplied to an annular space between said actuator ring element and a surrounding casing. Said elements may then be designed to provide a hydraulic plunger moving said actuator ring elements up and down. Such operating or actuator mechanisms are known and may be designed in many ways.